<?php
header("content-type:text/html;charset=utf-8");
// ==================php ：观察者模式 =============================
// 接口
interface Subject {
    public function Attach($Observer); //添加观察者
    public function Detach($Observer); //踢出观察者
    public function Notify(); //满足条件时通知观察者
    public function SubjectState($Subject); //观察条件
}
// 抽象类
abstract class Observer {
    protected $_UserName;
    protected $_Sub;
    public function __construct($Name, $Sub) {
        $this->_UserName = $Name;
        $this->_Sub = $Sub;
    }
    public abstract function Update(); //接收通过方法
}
// 被观察者。
class Boss Implements Subject {
    public $_action;
    private $_Observer;
    public function Attach($Observer) {
        $this->_Observer[] = $Observer;
    }
    public function Detach($Observer) {
        $ObserverKey = array_search($Observer, $this->_Observer);
        if ($ObserverKey !== false) {
            unset($this->_Observer[$ObserverKey]);
        }
    }
    public function Notify() {
        foreach ($this->_Observer as $value) {
            $value->Update();
        }
    }
    public function SubjectState($Subject) {
        $this->_action = $Subject;
    }
}
class StockObserver extends Observer {
    public function __construct($name, $sub) {
        parent::__construct($name, $sub);
    }
    public function Update() {
        echo $this->_Sub->_action . $this->_UserName . " 你赶快跑...";
    }
}

$huhansan = new Boss(); //被观察者
$gongshil = new StockObserver("三毛", $huhansan); //初始化观察者
$huhansan->Attach($gongshil); //添加一个观察者
$huhansan->Attach($gongshil); //添加一个相同的观察者
$huhansan->Detach($gongshil); //踢出基中一个观察者
$huhansan->SubjectState("警察来了"); //达到满足的条件
$huhansan->Notify(); //通过所有有效的观察者
